This application is a National Phase of PCT/EP2004/011095, filed Oct. 5, 2004, and claims the priority of German patent document DE 103 48 939.8, filed Oct. 18, 2003, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a headrest for a vehicle seat, with a stationary support part and an impact element which can be moved relative to the latter.
A known headrest of the generic type disclosed in German patent document DE 102 02 598 A1 has a stationary support part and an impact element which can be moved relative to the latter. The two are connected to each other via upper and lower levers which form four-bar linkages. The impact element can be moved relative to the stationary support part by pivoting the levers so as to actuate the four-bar linkage. Such pivoting of the impact element relative to the stationary support part occurs in two different situations. First, by pulling the impact element forward, a desired comfortable distance can be set between head and headrest. A locking device locks the four-bar linkages, and keeps the impact element in position once it is set. Second, such moving can also be induced by a crash, via the four-bar linkage as described previously. While the adjustment for comfort purposes is carried out manually, the crash-active adjustment is performed by a drive unit.
One object of the present invention is provides an improved headrest for a vehicle seat with a stationary support part and an impact element that can be moved relative to the latter.
Another object of the invention is to provide such a headrest which is simple and can be manufactured cost effectively.
These and other objects and advantages are achieved by the headrest configuration according to the invention, in which a lever system provided between the impact element and support part can be at least partially decoupled, so that different sequences of movement are possible between the support part and impact element, depending on the reason for which such a movement takes place. Such independence of movement makes it possible to set each sequence of movement separately, and thus to provide an ideal sequence of movement for each triggering situation. In addition, the provision of two different locking systems is unnecessary.
According to one embodiment of the invention, the impact element is mounted on the support part via at least one lower lever and one upper lever. The connection via two levers constitutes a simple lever system which can be made sufficiently robust to absorb forces acting on the impact element during an accident.
It is also possible to provide a pair of levers at the bottom and top, which makes the mounting of the movable impact element more stable. The use of pairs of levers therefore supports a robust and reliable mounting of the impact element on the stationary support component. The upper and lower levers can be mounted pivotably in each case both on the stationary support part and on the movable impact element, so that they form a four-bar linkage in each case.
In still another embodiment, a hinge point of the four-bar linkage is mounted displaceably, so that the four-bar linkage can be decoupled, so as to permit different sequences of movement via the same lever arrangement. If the displaceably mounted hinge point of the four-bar linkage is locked, the sequence of movement is characterized by a pivoting of the levers about the four-bar linkages, so that the movement of the impact element relative to the stationary support part is distinguished by a combination of a pivoting movement with a translation movement. Depending in each case on the arrangement of the levers, the impact element can thereby be displaced forward (i.e., toward the vehicle occupant's head), and also downward or upward. When the displaceably mounted hinge point of the four-bar linkage is unlocked, a different sequence of movement becomes possible, which is distinguished by pivoting of at least one lever with the impact plate about a hinge point. This type of movement makes it possible to set both the distance of the impact element from a vehicle occupant's head and the inclination of the impact element.
The displaceably mounted hinge point can be a bolt which is mounted in an elongated hole, and can be pressed into the elongated hole, so as to lock the hinge point in the mounting. As a result, the elongated hole achieves a defined frictional value against the bolt. In order to adjust the hinge point in the elongated hole, a minimum force must first be overcome. This arrangement has the advantage that it can be produced in a simple and material-saving manner. It constitutes a simple possibility of locking a hinge point in a mounting.
The different sequences for moving the impact element in different situations include, for example, transfer of the impact element from a normal position into a protective position in the event of an accident, in order to protect the vehicle occupant against injuries. The protective position is defined in such a manner that it prevents a vehicle occupant's head from swinging back in the event of an accident, and therefore prevents injuries.
The transfer from the normal position into the protective position can take place via the four-bar linkage. Pivoting via the four-bar linkage has the advantage that a reliable and specifically predeterminable displacement of the impact element relative to the stationary support part is possible.
According to a further embodiment, the impact element can be adjusted in its normal position for comfort reasons. In this case, the adjustment can take place by via the decoupled four-bar linkage. For example, the comfort adjustment can take place via a movement of the displaceably mounted hinge point of the four-bar linkage.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.